1. Field of the Invention
The present invention relates to a drive device of a vibrator drive type of liquid droplet discharge head, which discharges liquid droplets from a discharge section by extending and retracting a piezoelectric vibrator, a film manufacturing device, a drive method of a liquid droplet discharge head, a film manufacturing method, and an electronic equipment and an device production method.
Priority is claimed on Japanese Patent Application No. 2002-223153 and Japanese Patent Application No. 2003-072336, the contents of which are incorporated herein by reference.
2. Description of Related Art
Vibrator drive type liquid droplet discharge heads, which discharge liquid droplets by extending and retracting a piezoelectric vibrator, are used in liquid droplet discharge devices referred to as ink jet printers used in liquid crystal display panel production devices and printing devices of computer terminal. Piezoelectric vibrators are composed of components that include a piezoelectric element, and are extended and retracted according to an input drive waveform (for example, a voltage waveform).
In a drive device of a liquid droplet discharge head composed in this manner, the piezoelectric vibrator is driven by a voltage waveform composed of a trapezoidal wave as shown in FIG. 15. For example, potential Vcom in FIG. 15 is a predetermined applied voltage value of the piezoelectric vibrator, potential VH is a voltage value at which the piezoelectric vibrator is maximally retracted relative to the direction of liquid droplet discharge, while VL is a voltage value at which the piezoelectric vibrator is maximally extended relative to the direction of liquid droplet discharge. In the case of a layered piezoelectric element, the piezoelectric vibrator maximally retracts relative to the direction of liquid droplet discharge when the applied voltage has reached potential VH, and as a result of the applied voltage reaching potential VL, it is released from that retraction and extended, causing it to be displaced in the direction of liquid droplet discharge by inertia beyond displacement 0 of a so-called stationary state. The liquid droplet discharge device discharges liquid droplets by this extension and retraction operation of a piezoelectric vibrator.
Here, an explanation is provided of the operations of a piezoelectric vibrator respectively corresponding to times T1 through T5 of the voltage waveform shown in FIG. 15. At time T1, the applied voltage to the piezoelectric vibrator is increased from potential Vcom to potential VH. Thus, at time T1, the amounts of extension and retraction of the piezoelectric vibrator increase. At time T2, since a constant potential VH is applied to the piezoelectric vibrator, the piezoelectric vibrator attempts to reach a constant (maximum) amount of extension and retraction. At time T3, since the applied voltage decreases from potential VH to potential VL, the amounts of extension and retraction of the piezoelectric vibrator decrease. At time T4, since a constant potential VL is applied, the piezoelectric vibrator attempts to reach a constant (minimum) amount of extension and retraction. At time T5, since the applied voltage increases from potential VL to potential Vcom, the amounts of extension and retraction of the piezoelectric vibrator increase. As a result of these times T1 through T5 being repeated, the piezoelectric vibrator extends and retracts to discharge liquid droplets from the liquid droplet discharge head of a liquid droplet discharge device.
However, since the piezoelectric vibrator repeats the mechanical operations of extension and retraction, the element itself becomes fatigued and deteriorates. Due to increases in the thermal load that results from sudden extension and retraction as well as increases in the mechanical load resulting from sudden changes in operation from the extension and retraction to the stopped state, deterioration of the element is thought to be accelerated, thereby shortening its service life.
However, in a drive device of a liquid droplet discharge head according to the previously described prior art, as shown in FIG. 15, since the piezoelectric vibrator is driven by the voltage waveform of a trapezoidal wave, the operating state of the piezoelectric vibrator changes suddenly at each transition point A0 through A5 of the waveform. Thus, as previously mentioned, the mechanical and thermal loads on the piezoelectric vibrator increase, thereby resulting in the problems of accelerated deterioration of the element and prevention of discharge of stable liquid droplets from the liquid droplet discharge head for a long period of time.
In consideration of the aforementioned problems, an object of the present invention is to provide a drive device of a liquid droplet discharge head, a film manufacturing apparatus, a drive method of a liquid droplet discharge head, a film manufacturing method, and an electronic equipment and device production method that enable the operation of discharging stable liquid droplets to be performed over a long period of time by inhibiting deterioration of the piezoelectric vibrator.